1. Field of the Invention
Aspects of the present invention relate to a technology that enables a relay station belonging to a multi-hop network to predict delay which can be generated and to determine an order of processing service packets with a plurality of quality of service (QoS) levels.
2. Description of the Related Art
A relay station economically and efficiently extends a cell coverage of a base station and increases a data transmission rate. Accordingly, much research on a communication system using a relay station has been conducted. A technology related to a multi-hop network including a plurality of relay stations is coming into the spotlight. For example, the Institute of Electrical and Electronics Engineers (IEEE) 802.16e specifies details about a multi-hop network including a plurality of relay stations.
When configuring a multi-hop network using a plurality of relay stations, service packets transmitted from a source node are transmitted to a destination node via the plurality of relay stations. The plurality of relay stations processes the received service packets using various methods, and transmits the processed service packets to a neighboring relay station or the destination node. Delay is generated while each of the plurality of relay stations processes the service packets.
Each of the service packets can have quality of service (QoS) levels different from each other, and require a delay condition based on the QoS levels. For example, a delay condition required by a service packet A and a delay condition required by a service packet B may be different.
When a relay station receives a plurality of service packets, processing the plurality of received service packets based on the order in which the plurality of received service packets are received may be problematic. For example, a relay station may first receive a service packet A and then receives a service packet B. If the service packet B requires a more strict delay condition than the service packet A and the relay station processes the service packet A first, a delay condition required by the service packet B cannot be satisfied. Thus, a technology enabling a relay station to determine an order of efficiently processing received service packets based on QoS levels of the received service packets is desirable.